Ogiso-Ono Y, Ikenishi K
Department of Biology, Faculty of Science, Osaka City University, Sugimoto, Osaka, Japan.
Dev Growth Differ. 1999 Dec;41(6):745-50. doi: 10.1046/j.1440-169x.1999.00475.x.
In order to understand the cause for the decreased number of primordial germ cells (PGC) in Xenopus albino (a(p)/a(p)) tadpoles, the number of presumptive PGC (pPGC) in the albino and wild-type embryos at Nieuwkoop and Faber's stages 6-37/38 were examined using the antibody specific to germ plasm. The positions of pPGC in the endodermal cell mass in embryos of both types at stages 28 and 33/34 were also observed to learn the migratory behavior of pPGC. The number of pPGC in the albino increased up to stage 28 with development, but decreased thereafter. In contrast, the number in the wild-type increased to stage 33/34 as development proceeded, and the number of pPGC in stage 33/34 embryos reached nearly that of PGC of the feeding tadpoles in the same batches. Judging from the positions of pPGC, the migration of pPGC from the median part through the lateral to the dorsal part of the endodermal cell mass in the albino was suspected to be somewhat later than that in the wild-type. These results, together with the results in previous studies, suggest that the decreased number of PGC in the albino would be closely related to the sudden decrease in number of pPGC at stage 33/34, as well as to the ectopic position of pPGC in endodermal cell mass, the latter of which had already been demonstrated to be responsible for the differentiation into PGC.
为了了解非洲爪蟾白化品系（a(p)/a(p)）蝌蚪中原始生殖细胞（PGC）数量减少的原因，我们使用针对生殖质的特异性抗体，检测了处于Nieuwkoop和Faber分期6 - 37/38的白化品系和野生型胚胎中推定原始生殖细胞（pPGC）的数量。我们还观察了两种类型胚胎在28期以及33/34期内胚层细胞团中pPGC的位置，以了解pPGC的迁移行为。白化品系中pPGC的数量在发育至28期时增加，但此后减少。相比之下，野生型中pPGC的数量随着发育进程增加至33/34期，且33/34期胚胎中pPGC的数量几乎达到了同一批次摄食期蝌蚪PGC的数量。从pPGC的位置判断，白化品系中pPGC从内胚层细胞团中部经侧面迁移至背部的过程似乎比野生型稍晚。这些结果，连同之前研究的结果表明，白化品系中PGC数量的减少与33/34期pPGC数量的突然减少密切相关，也与pPGC在内胚层细胞团中的异位位置有关，后者已被证明是导致其分化为PGC的原因。
